An electrostatic actuator is known in which an electrostatic force is caused to act between a stator and a mover that are included in the actuator, and the mover is driven by the attraction force of the electrostatic force. Extremely small electrostatic actuators that use so-called semiconductor process technology (manufacturing technology of semiconductor devices) are being developed in fields such as MEMS (Micro Electro Mechanical Systems) and the like. In the fields of MEMS and the like, a so-called MEMS switch that utilizes an electrostatic actuator is known.
In electrostatically-driven MEMS switches, it is desirable to reduce the pull-in voltage, ensure creep resistance, or increase the reliability of hot switching and the like.